Primer – CSS Toolkit and Guidelines that Power GitHub
Primer is the CSS toolkit that powers GitHub’s front-end design. It’s purposefully limited to common components to provide our developers with the most flexibility, and to keep GitHub uniquely GitHubby. It’s built with SCSS and available via Bower, so it’s easy to include all or part of it within your own project.
It is available for use under the MIT license and built with open source projects like SCSS, Jekyll, Grunt, and more. It includes a small Gruntfile for compiling SCSS, Autoprefixer for vendor prefixes, and Parker for CSS stats.
License: MIT License